The most common sources of roughage for horses are pasture and baled hay, although beet pulp, alfalfa or hay cubes, and bagged chopped forage are viable options in many circumstances.
For horses just beginning to experience dental problems, choice of hay and the manner in which it is presented can mean the difference between eating the hay or "quidding" (wadding the hay into balls, then spitting it out.) First cutting grass hays and alfalfa hays are usually quite coarse and stemmy. Second cutting grass hays are generally very leafy, with few stalks or seed heads, and easier to chew.
When serving hay to elders, it sometimes helps to "shake out" the flakes or books. A loose pile of individual strands allows a horse to pick up smaller mouthfuls than a compacted hay flake permits. (One disadvantage, however, to loose hay piles is their tendency to travel long distances on windy days. Choose a sheltered location when possible.)
Placement of hay can be very important when feeding several horses in one field. Large round bales are often not the best choice for elders, especially when feeding a large group of horses. A large number of horses forced to push toward a single food source is a very unnatural way for these animals to forage. Timid horses do especially poorly in this stress laden situation.
A much better way to feed hay to elders (or any groups with submissive horses) is to divide the hay into more portions than there are horses, and place the portions several horse lengths apart. Appropriate spacing of enough hay piles ensures that timid or weak horses will have access to their share.
The horses shown grazing above have voluntarily chosen approximately three body lengths each as their comfort zones. Placing hay portions in a comparable pattern ensures all three can eat in comfort.
In the photo below, the two mares on the left are young, dominant animals who are very comfortable with each other. The mare on the right is a more timid elderly animal. She needs a greater space around her to eat in a relaxed manner. (Note the loosely piled hay as mentioned above.)
Spacing numerous hay piles some distance apart has a second benefit. It allows horses to mimic the meandering fashion in which they graze. Horses wander from one pile of hay to another just as they wander from one patch of grass to the next. It is unnatural for a horse to stand in one spot to eat for long periods of time. The horse's digestive system evolved to serve an animal "on the move," and functions best when he is allowed generous opportunity to perform that movement at will.